serves

I feel like I am not transferring energy into my serves properly: -I am curled up at the point of extension -Follow through is broken -idk if I am jumping too early -it is prone to breaking down when matches get tight (both 1st and 2nd serves) I would be interested in feedback based on these...

Does "Next Gen" struggle more with double-faulting than any other generation of players? We've seen a ton from Felix 2A, Zverev, and even Tsitsipas, Khachanov a bit. Maybe I'm just noticing it more b/c I'm working through it currently too but the last few weeks seem like it's everywhere singles...

I am looking for a coach to help my 11 yr old improve on serves and overall improvement. His serve are very weak with double faults and he looses because of that. I need someone in the vicinity of central NJ. Please recommend few coaches who can help him improve. Thank you for your help in...

For the "basic" 3 types of serves, topspin, flat, & slice - why not change the grip slightly for each one instead of changing the toss location? Thanks for any and all answers.